your LHS sold it to you as BNF (everything but Tx)? that's a good deal. Wise of you to replace the motor, ESC, (and hopefully the Rx) for your new Apprentice. Better electronics usually = longer lifespan.

To answer your question about the Power-Up-25 motor and similar set-ups, I'm running a Hacker A30-10XL 900kV 650W with the Eflite 40 Amp Pro ESC and 11x8 APCe prop. My Hacker's kV and Watts are very close to your Power-Up-25.
On 3s, that setup is really similar to the Eflite Power 15 950kV motor, which is decent power for training, normal flying, and mild aerobatics, but on 4s, my Apprentice has TONS of power. Around 187 watts per pound which is well into the 3D power range. Basically unlimited vertical (though it isn't balanced for it), and much faster (but it tends to climb due to the high lift of the wing)

I think you'll like that setup on your Apprentice (though I'd go with the APC 11x7, rather than the 11x5.5 which may not give you much power on 3s, but check it with your watt meter). The capability of flying 3s or 4s with the same motor and prop is nice.

Have fun!

Yup, sold it as a BNF, I was quite happy

With a 4s battery it definitely sounds more exciting, but for now I will be running on a 3s battery as I have three of them. But I am definitely tempted to get a 4s to see the difference lol

So you are saying to get a 11x7 prop so that I can use it with a 3s and 4s battery? Im worried that prop might give me a trouble with a 4s because on the site it does not list a 11x7 as a test prop...

Maybe you got one that had been sitting on a shelf for awhile. You said you bought it from your Local Hobby Store.

Actually the Power-Up-25 does list 11x7 under 3s, but not 4s. the 11x5.5 is under 3s as well, but not 4s. On my Hacker 900kV 650W it puts out just about exactly 650 watts at full throttle on 4s with an 11x8 battery. But I live at 5000 ft altitude which would affect it some. That's why you should check it with your watt meter.

So Bobly, did you get that tail heavy issue you had with your Apprentice fixed? How about the prop adapter and set screw?

Haven't got to fly again -darn weather. I sent a querry to Horizon about the adapter. Started to fix it back, then check one of the close hobby shops and they had the collet type prop adapter which I like a lot better, so went and picked it up and now it is all better. That factory prop adapter has the smallest set screw I have ever seen holding it to the shaft. It doesn't have but three threads on it. Not sure what happened whether it wasn't tight to start with or worked loose. I got it out of the adapter, cleaned things up so the shaft would go back in the adapter, but there wasn't enough thread material left in the aluminum adapter to hold. I tapped the hole out to 6-32 threads and stuck it in the parts box for possible later need somewhere.

Well can't wait to get my new motor installed and see how much faster it is Should be here next week. I may order a 4s battery in a few weeks because I don't think I will get the best results with my 3s.

It'll probably be a little faster, but don't expect a night-and-day difference.

The stock motor is an 870kV, and your new Power-Up-25 is a 950kV. Higher, but not dramatically higher. The difference is only 80kV, and 80kV X 11.1V = about 900 RPM's higher. That won't equate to much additional speed.

Depending on the new motor's efficiency, you may see a little longer flight times. The big difference will come when you decide to try 4s. THAT will give you significantly more speed. Just remember, though, the Apprentice is a trainer, not a pylon racer. Its huge wing provides a lot of lift, but also creates a lot of drag.

I don't plan on making it a wild racer, as you said it is a high wing trainer. But I just don't trust that stock plastic housing motor, which is mainly why I wanted to replace it. And of course to get a bit more speed.

I can also experiment with different sized props with my 3s batteries?

all you have to do is call HH and tell them your motor is cracked and you didnt crash it. And they will send you out a new design version of the complete metal endbell motor. Thats what they did for me.